In the conventional gas turbine, it has been known a portion of compressed air bled from a compressor and a bled air is discharged into an exhaust duct through an air bleeder tube (for example, Patent Document 1 as described below).
FIG. 7 is a schematic view for showing one example of a conventional gas turbine. As shown in FIG. 7, the conventional gas turbine comprises a rotor 10 for rotating around a rotational axis, a plurality of rotor blades 11 circularly mounted at the rotor 10, a turbine casing 12 for surrounding and covering the rotor 10, a plurality of stator blades (not shown) mounted on the turbine casing 12, wherein the plurality of the rotor blades 11 and the plurality of the stator blades are alternatively arranged along the rotational axis. As shown as an arrow F in FIG. 7, the main flow of the combustion gas 13 is directed among them. Each rotor blade 11 and each stator blade are made as one pair. These pairs make a multi stage structure. FIG. 7 shows the rotor blade of the last stage located at the lower most side with respect to the main flow.
At the downstream side of the last rotor blade 11 with respect to the main flow, an exhaust diffuser 14 is coaxially connected. The exhaust diffuser 14 of which an inside is connected to the main flow of the combustion gas 13 comprises an exhaust casing 16 of which an inside forms a main flow of combustion gas 15 of which a cross sectional area is gradually enlarged along the direction of the main flow, a plurality of struts for surrounding and supporting a bearing 17 for supporting the rotor passed through the inside of the exhaust casing and manholes 19 in which an operator walks for a checking operation and a maintenance operation. At the downstream side of the exhaust diffuser 14 with respect to the main flow, a cylindrical exhaust duct 20 is coaxially connected.
In the conventional gas turbine, an air bleeder tube 100 is arranged inside of an exhaust duct 20.